Dušan Ponikvar

Generator of pseudo random pulses

Abstract The described random pulse generator produces TTL compatible pulses, random in time. The rate of the pulses can be preset to different values from 2500 to 100000 s−1 in steps of 2500 s−1. The rate is controlled by a quartz crystal. Minimum time interval between two successive random pulses is 97.6 ns. The generator was designed for testing and calibrating of dead time correction algorithms in spectroscopy systems.

WILKINSON-TYPE ADC WITH SHORT CONVERSION TIME AND LOW CLOCK FREQUENCY

Abstract Two types of ADCs are used in nuclear spectroscopy. These are the Wilkinson-type ADC and the successive approximation ADC. The Wilkinson-type ADCs are superior in channel profile and differential linearity over successive approximation ADCs. They are, however, relatively slow. The design presented joins the best from both: fast conversion time combined with good channel profile by the use of the “nonium” principle for measurement of time.

Compact radioactive aerosol monitoring device for early warning networks.

In the frame of the European metrological research project MetroERM, a compact portable aerosol sampling and measurement device was developed at Jožef Stefan Institute. The system incorporates a CeBr3 scintillation detector positioned centrally within a concertinaed filter assembly and an improved high flow rate air pump. It provides continuous on-line low level airborne radioactive particulate monitoring for field station use via 3G network communications. The calibration of the device was performed at National Physical Laboratory (NPL) with filters, spiked with a certified mixed nuclide solution. Additionally first tests were performed in an environment with an elevated radon concentration.

RMS noise meter

The performance of a high-resolution spectroscopy system is affected by the noise properties of the spectroscopy amplifier. A new approach for measurement of the noise at the output of the spectroscopy amplifier is presented.

Dead time correction using a timer

Abstract Dead time correction algorithms are implemented in spectroscopy systems. They reduce errors in the determination of the rate of incoming pulses. An improvement of a known dead time correction algorithm is presented. The improvement is supported by results of simulation.

Evaluation of the radon interference on the performance of the portable monitoring air pump for radioactive aerosols (MARE)

A compact portable aerosol sampling and measurement device was developed at Jožef Stefan Institute (JSI). A CeBr3 scintillation detector is positioned centrally within a concertinaed filter assembly. It provides continuous and via network communications on-line monitoring of low levels of airborne radioactive particulates. The evaluation of the response of the device to the natural background at controlled conditions with elevated radon concentrations, performed at the National Institute of Ionizing Radiation Metrology of ENEA, is presented.

A novel ultra-low power liquid crystal display light shutter driving scheme

A novel liquid crystal display (LCD) driving concept for light shutters is shown here, based on driving signal polarity reversal controlled by the driving voltage integral across the LCD switching element electrodes, as opposed to plain periodic polarity reversal. This driving scheme optimizes the DC driving signal voltage balancing and guarantees compensation of the long-term (DC) component of the driving voltage within one polarity reversal cycle, irrespectively of driving voltage amplitude variations. The possibility of using low driving frequencies reduces the LCD switching elements power consumption significantly compared to standard driving techniques, which is important for portable devices such as welding light shutters.

Simple drive system for Mössbauer spectroscopy

Abstract A simple driving system for generating photons with flat energy spectrum by the Doppler effect is described. The classical double-loudspeaker design with electronic feedback is replaced with a single loudspeaker and smart driving electronics, that uses low cost microcontrollers and DACs.